More than 20 people have been killed in New York and the wider US north-east as the remnants of Hurricane Ida brought unexpected levels of heavy rain and flooding.

The deaths and damage spanned huge areas in New York, New Jersey, Pennsylvania, Connecticut and Maryland. Officials blamed many of the fatalities on basement apartments becoming filled with water.

Rivers and creeks swelled to record levels, roadways flooded and transportation systems were badly impacted.

The ferocious storm, downgraded from the hurricane that hit Louisiana in the south of the US earlier in the week, also spawned tornadoes, including one that ripped apart homes and toppled silos in Mullica Hill, New Jersey, south of Philadelphia.

Videos shared on social media showed subway platforms in Manhattan and Brooklyn submerged with flood water and cars in the city struggling to pass flooded streets.

At least 22 people have been killed, according to the Associated Press. Reports included:

Nine people died in New York City, eight of them when they became trapped in flooded basements, and one who drowned in a car, according to police.

At least eight people have been killed in New Jersey, officials said. They included four people who were found dead in an apartment complex in Elizabeth, New Jersey, the city’s mayor and spokesperson told local media. In Passaic, New Jersey, a 70-year-old man was swept away after his family was rescued from their car, and reported to have drowned.

Three people were killed in Pennsylvania’s suburban Montgomery county; one was killed by a falling tree, one drowned in a car and another in a home.

Outside Philadelphia, officials reported “multiple fatalities”, saying no additional details were immediately available.

A 19-year-old man was killed in flooding at an apartment complex in Rockville, Maryland, police said.

Rescuers were searching for more stranded people and braced for potentially finding more bodies. In Connecticut, an on-duty state trooper and his cruiser were swept away in flood waters on Thursday morning in Woodbury, and the trooper was taken to a hospital, state police and local authorities said.

The deaths in New York city included a 50-year-old man, a 48-year-old woman and a two-year-old boy who were found unconscious and unresponsive late Wednesday inside a home.

“We’re enduring an historic weather event tonight with record breaking rain across the city, brutal flooding and dangerous conditions on our roads,” said the mayor, Bill de Blasio, while declaring a state of emergency in New York City late Wednesday.

The mayor’s warning came as the National Weather Service (NWS) office in New York issued its first set of flash flood emergencies in the region on Wednesday night, alerts only sent in the most dangerous conditions.

“There’s a lot of hurt in New Jersey,” Murphy told ABC’s Good Morning America on Thursday as he discussed damage caused by flooding in the northern part of the state and tornadoes in the southern part of the state.

In New York City, officials banned travel for all but emergency vehicles until early Thursday and warned against unnecessary travel into the morning. Some subway and rail service had resumed on Thursday morning.

Newark international airport shut down on Wednesday night as videos showed water rushing through a terminal. The airport was allowing limited flights on Thursday.

Officials said 370 flights have been canceled so far.

Amtrak service was canceled between Philadelphia and Boston, resuming in limited capacity on Thursday morning. New Jersey Transit train service remained suspended with the exception of the Atlantic City line. Buses were running with myriad cancelations and delays. Transit officials cautioned against traveling unless it was “absolutely essential”.

Major flooding along the Schuylkill River in Pennsylvania swamped highways, submerged cars and disrupted rail service in the Philadelphia area.

At least 220,000 customers were without power in the region, with most of the outages in New Jersey and Pennsylvania. More than 35,000 customers were without power on Thursday morning in New York City, Long Island and its northern suburbs.

Police in Connecticut were investigating a report of a person missing due to the flooding in Woodbury. In Plainville, Connecticut, authorities said they used boats to rescue 18 people from a flooded neighborhood.

The devastation in the north-east of the country comes after Hurricane Ida struck Louisiana on Sunday as the fifth-strongest storm to ever hit the US mainland, leaving 1 million people without power, maybe for weeks.

New York City’s resilience to flooding was under scrutiny; this is the second time in recent weeks that subway stations and streets have been submerged with flood water.

The Biden administration has pledged to tackle climate change but this week it was being criticized by environmental groups after resuming drilling auctions for oil and gas exploration.

Early on Thursday in New York City’s Central Park about 10 trees were upended on the south side and some localized flooding caused by damaged structures blocking drains but no major damage otherwise.

The NWS recorded 3.15in (8.9cm) of rain in Central Park in one hour on Wednesday night, far surpassing the previous recorded high of 1.94in (4.9cm) that fell in one hour during Hurricane Henri on 21 August. Scientists have warned such weather extremes will be more common with manmade global warming.

Most uptown subway stations were open but service remained extremely limited.

The Associated Press contributed to this report.